I know that the Kin-slaying was done there and also that Melkor had quite a long time (I'm not sure of the timespan between the creation and the First Age around when Melkor came to Middle Earth.) that even the Undying Lands and the Blessed Realm weren't marred by his evil influence. I do know, if I recall correctly, that death itself, at least for the non-Elves, was not originally created, as it was in our timeline, as a punishment for evil, but rather as a relief perhaps (the immortality of the Elves was purchased at the price of the tragic memory of evil wrought by Melkor, Sauron, dragons, men, and even other Elves, plus remembering things as they were before they were corrupted.) Thus, if Bilbo, Frodo, Sam, and Gimli were to eventually die of old age in the Blessed Realm, it was the design of Eru rather than due to sin because of the corruption of Melkor. Not that wickedness didn't make death come sooner, as their evil deeds appeared to have shortened the lifespan of the Numenoreans, making them vulnerable to Sauron's suggestion of going to the undying lands where they would never die (though they were outright told that it was not so.) More to the point, if Valinor was originally attached to and part of Middle Earth, it seems odd that Mair and Elves that lived there wouldn't end up fading in the end just as they would if they'd stayed in Middle Earth. It appears that Middle Earth got the worst of the malice of Melkor, but how did Valinor and the Undying Realm fare?